Paper machine headbox



June 3 19.59 K. c. LOGAN ET AL PAPER MACHINE HEADBOX Filed Sept. '29, 1955 QZL United States Patent PAPER MACHINE HEADBOX Kenneth C. Logan and James Mardon, Quebec City, Quebec, Canada, assignors to Anglo Paper Products, Limited, Quebec City, Quebec, Canada Application September 29, 1955, Serial No. 537,531 3 Claims. (Cl. 162-344) This invention relates to paper machine headboxes.

The desirable achievement of a stabilized and equalized flow of pulp stock from the slice of a paper machine onto the wire has in the past been diflicult to attain under all circumstances of operation and has resulted in problems which have not been satisfactorily solved.

A general object of the present invention is to provide a headbox having a slice incorporated therein and which results in the production of an even stabilized flow of stock onto the wire across the width of the machine.

To this end, the invention comprises the provision of a headbox having converging walls constituting a slice nozzle, said converging walls extending across the width of the paper machine and having substantial length thereby to provide a stabilizing and pressure equalizing effect on the stock flow therebetween in a direction perpendicular to the convergence of the walls.

The invention will be described with reference to the accompanying drawing, the single figure of which is a sectional end elevation of a headbox in accordance with the invention.

There is disclosed in Figures 7, 11 and 17 of copending application Serial No. 529,696 a headbox wherein a major portion of the box is constituted by converging walls forming a slice nozzle. A disadvantage in such a structure is that it cannot be used for low speed machines wherein the eifective head, needed to obtain a jet speed equivalent to wire velocity, is approximately equal to, or less than, the depth of the box at its deepest point.

This disadvantage is overcome in the headbox illustrated, wherein 1 is the breast roll, 2 the wire, and 3 the headbox in accordance with the invention. As shown, the headbox 3 has a horizontally disposed top wall 4 located slightly above the forming portion of the wire and an inclined bottom wall 5 located generally below the forming portion of the wire. The bottom wall 5 converges towards the top wall from a point remote from the wire towards the wire to form the nozzle opening 6. It will be apparent that the terminal edge portions of walls 4 and 5 constitute slice lips defining the nozzle opening 6. Stock may be fed to the box by any suitable means, such as a perforated feed roll 7 as disclosed in copending application Serial No. 529,696. Perforated rolls 8 and 9 may also be mounted on the box further to promote evenness of flow. It will be apparent that, in the headbox illustrated, the effective head due to the depth of stock in the box is zero and the box can be used for low pressure machines since the pressure outside the feed roll is sufficient.

It will be observed that the stock feed conduit 7 is located between the walls 4 and 5 and substantially horizontally opposite the nozzle opening 6 and in a zone of the headbox remote from the slice lips. It will also be observed that the converging walls 4 and 5 are plane from the zone of the feed conduit 7 to the slice lips and extend across the width of the machine. Thus, walls 4 and 5 constitute the major wall area of the headbox thereby to provide a stabilizing and equalizing effect on paper stock flow therebetween in a direction perpendicular to the convergence of the walls.

We claim:

1. A paper machine headbox having top and bottom converging walls, terminating in slice lips, said lips defining a nozzle opening for paper stock, and a stock feed conduit extending transversely into said headbox, said conduit being located between said top and bottom walls and substantially horizontally opposite said noule opening and in a zone of said headbox remote from said slice lips, said headbox being otherwise closed, said converging walls being essentially plane from the zone of said conduit to said slice lips and extending across the width of the paper machine and constituting the major wall area of said headbox thereby to provide a stabilizing and equalizing effect on paper stock flow therebetween in a direction perpendicular to the convergence of said walls.

2. In a paper machine having a breast roll and a paper forming wire thereon, a headbox having a horizontally disposed top wall located slightly above said wire, a bottom wall converging towards said top wall from a point below said wire, said walls terminating in slice lips adjacent said wire, said slice lips defining a nozzle opening for paper stock, and a stock feed conduit extending transversely into said headbox, said conduit being located between said top and bottom walls and substantially horizontally opposite said nozzle opening and in a zone of said headbox remote from said slice lips, said headbox being otherwise closed, said top and bottom walls being essentially plane from the zone of said conduit to said slice lips and extending across the width of the paper machine and constituting the major wall area of said headbox.

3. In a paper machine having a breast roll and a paper forming wire thereon, a headbox having converging top and bottom walls terminating in slice lips adjacent said wire, said lips defining a nozzle opening for paper stock, and a stock feed conduit extending transversely into said headbox, said conduit being located between said top and bottom walls and substantially horizontally opposite said nozzle opening and in a zone of said headbox remote from said slice lips, said headbox being otherwise closed, said converging walls being essentially plane from the zone of said conduit to said slice lips and extending across the Width of the paper machine and constituting the major wall area of said headbox, said bottom wall being disposed below the plane of said wire.

References Cited in the file of this patent UNITED STATES PATENTS 1,881,985 Von Hazmburg Oct. 11, 1932 2,062,741 Murray Dec. 1, 1936 2,203,802 Thaler June 11, 1940 2,205,693 Milne June 25, 1940 2,329,799 Thorsen Sept. 21, 1943 2,473,069 Niks June 14, 1949 2,550,552 Goodwillie Apr. 24, 1951 2,677,991 Goumeniouk May 11, 1954 2,728,271 Witworth et al Dec. 27, 1955 2,756,648 Lee July 31, 1956 2,756,649 Lee July 31, 1956 

